Carbon monoxide detector



FIG. 1 is a front elevational view of a carbon monoxide detector showing my new design;

FIG. 2 is a right side elevational view, the left side being an identical image;

FIG. 3 is a top plan view;

FIG. 4 is a bottom plan view; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a carbon monoxide detector, as shown. 